/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

package com.zhs.gccs.utils.zip.extra;


/**
 * This is a class that has been made significantly smaller (deleted a bunch of
 * methods) and originally is from the Apache Ant Project
 * (http://ant.apache.org), org.apache.tools.zip package. All license and other
 * documentation is intact.
 * 
 * Utility class that represents a two byte integer with conversion rules for
 * the big endian byte order of ZIP files.
 * 
 */
public final class ZipShort implements Cloneable {
	private static final int BYTE_1_MASK = 0xFF00;
	private static final int BYTE_1_SHIFT = 8;

	private final int value;

	/**
	 * Create instance from a number.
	 * 
	 * @param value
	 *            the int to store as a ZipShort
	 * @since 1.1
	 */
	public ZipShort(int value) {
		this.value = value;
	}

	/**
	 * Create instance from bytes.
	 * 
	 * @param bytes
	 *            the bytes to store as a ZipShort
	 * @since 1.1
	 */
	public ZipShort(byte[] bytes) {
		this(bytes, 0);
	}

	/**
	 * Create instance from the two bytes starting at offset.
	 * 
	 * @param bytes
	 *            the bytes to store as a ZipShort
	 * @param offset
	 *            the offset to start
	 * @since 1.1
	 */
	public ZipShort(byte[] bytes, int offset) {
		value = ZipShort.getValue(bytes, offset);
	}

	/**
	 * Get value as two bytes in big endian byte order.
	 * 
	 * @return the value as a a two byte array in big endian byte order
	 * @since 1.1
	 */
	public byte[] getBytes() {
		byte[] result = new byte[2];
		result[0] = (byte) (value & ZipConstants.BYTE_MASK);
		result[1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
		return result;
	}

	/**
	 * Get value as Java int.
	 * 
	 * @return value as a Java int
	 * @since 1.1
	 */
	public int getValue() {
		return value;
	}

	/**
	 * Get value as two bytes in big endian byte order.
	 * 
	 * @param value
	 *            the Java int to convert to bytes
	 * @return the converted int as a byte array in big endian byte order
	 */
	public static byte[] getBytes(int value) {
		byte[] result = new byte[2];
		result[0] = (byte) (value & ZipConstants.BYTE_MASK);
		result[1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
		return result;
	}

	/**
	 * Helper method to get the value as a java int from two bytes starting at
	 * given array offset
	 * 
	 * @param bytes
	 *            the array of bytes
	 * @param offset
	 *            the offset to start
	 * @return the corresponding java int value
	 */
	public static int getValue(byte[] bytes, int offset) {
		int value = (bytes[offset + 1] << BYTE_1_SHIFT) & BYTE_1_MASK;
		value += (bytes[offset] & ZipConstants.BYTE_MASK);
		return value;
	}

	/**
	 * Helper method to get the value as a java int from a two-byte array
	 * 
	 * @param bytes
	 *            the array of bytes
	 * @return the corresponding java int value
	 */
	public static int getValue(byte[] bytes) {
		return getValue(bytes, 0);
	}

	/**
	 * Override to make two instances with same value equal.
	 * 
	 * @param o
	 *            an object to compare
	 * @return true if the objects are equal
	 * @since 1.1
	 */
	@Override
	public boolean equals(Object o) {
		if (o == null || !(o instanceof ZipShort)) {
			return false;
		}
		return value == ((ZipShort) o).getValue();
	}

	/**
	 * Override to make two instances with same value equal.
	 * 
	 * @return the value stored in the ZipShort
	 * @since 1.1
	 */
	@Override
	public int hashCode() {
		return value;
	}

	@Override
	public Object clone() {
		try {
			return super.clone();
		}
		catch (CloneNotSupportedException cnfe) {
			// impossible
			throw new RuntimeException(cnfe);
		}
	}

	@Override
	public String toString() {
		return "ZipShort value: " + value;
	}
}
